1. Field of the Invention
The present invention relates to an input operation device utilized as a man-machine interface of electrical equipment such as personal computers, Personal Digital Assistants (PDAs), portable telephones, game devices, and car navigation devices.
2. Description of the Related Art
Pointing devices such as mice, trackballs, and touch panels are known as input operation devices provided to electrical equipment. Of those devices, trackballs and touch panels (touch pads) are advantageous, as compared to mice and the like, which require an operation space. For example, trackballs and touch panels may have unity with the equipment because they are built into the equipment itself. Focusing on the presence or absence of multi-functionality corresponding to the day-to-day pursuit of making electrical equipment more highly functional, the conventional trackballs have only a function of performing coordinate operations in which an indicator mark, such as a pointer, displayed on a screen of a display device is freely moved on the screen. It is necessary to conduct a key operation utilizing another input device, like an enter key of a keyboard, to perform input operations after moving the pointer to a predetermined position. Coordinate operations and input operations cannot both be completed by using only a trackball. Further, although coordinate operations are performed with conventional touch panels by touching the surface thereof using a finger, input operations are generally achieved by a computer software driver. For example, if the touch panel surface is tapped twice in succession, the driver recognizes the tapping as an input operation. It can therefore be said that the touch panel is superior to the trackball in that two functions, coordinate operations and input operations, can be achieved by a single input operation device. However, even though multi-functionality can be achieved by using computer software, the operational feel obtained from the touch panel by an operator who performs rubbing operations or tapping operations on the touch panel are always unchanging, hard, uniform feel.
Therefore, there is a need in the art for a pointing device having good operation as a man-machine interface.